Differences in cerebral blood flow following risperidone treatment in children with autistic disorder

OBJECTIVE: Functional changes in the brains of autistic children due to risperidone treatment and theirs relationship to the symptom clusters are yet unknown. In this autistic disorder case series we aimed to comparatively evaluate the clinical findings before and after risperidone treatment, and regional cerebral blood flow (rCBF) findings with 99mTc-hexamethylpropyleneamine oxime (HMPAO) brain SPECT. METHOD: Eleven autistic patients (age range: 6-7 years; 4 girls, 7 boys) received risperidone therapy (1.5-2.5 mg d(-1)) and were followed-up for 3 months. All the patients underwent neurologic examinations, psychometric examinations, and SPECT imaging, both at the start of risperidone treatment and 3 months after the treatment started. Clinical observations, and the observations of parents and teachers were recorded. These results were compared with cerebral perfusion indices obtained from SPECT data. RESULTS: After 3 months of treatment changes in rCBF were observed in various regions and to varying degrees. We observed relationships between clinical symptoms and pre-therapy rCBF findings, and between clinical improvement and rCBF changes. CONCLUSION: Findings in the present case series are the first to demonstrate a relationship between clinical improvement and regional perfusion patterns after risperidone treatment. We think that these findings may contribute to the understanding of the neurofunctional mechanisms and hypothetical models of autism.